Dump Truck Hydraulic Lines

[leadfarmer]

I bought a 1981 Kodiak C70 dump truck. It had a plow and salt spreader. The hydro pump is engine belt driven with an electric solenoid to engage it (switch on the dash).

I have removed everything for the front plow - 3 hydro lines ran to the front from the valve block, and the two cable control levers in the cab.

I have removed everything for the rear spreader and auger. The pump fed the 3 way flow diverter box shown in the attached pictures. The diverter box split fluid to the valve block and to the variable flow control box in the cab which controlled flow to the auger and spreader. The variable flow in the cab had two hydro lines going to the back and a return to tank line. There was also another return to tank line from the back to the tank for the return from the spreader and auger.

So, one thing I don't understand is why the power beyond port on the valve block is connected to the other side of the flow diverter box which fed the variable flow control.

The attached picture with notes on it shows what I have after removing the above.

I was tempted to plug the power beyond outlet on the valve block and remove the flow diverter box, connecting the pump directly to the valve block.

I think the valve block has a pressure relief valve and it has a return to tank line, so I think this is ok?

Yesterday I fired it up and tested it. If I held the dump lever in the UP position and turned on the pump it worked as it should. When travel stopped and control lever returned to center it seemed like the pump was working harder. Lower pitched noise, not a high pitch maxed out pressure noise.

If I turned on the pump with the control lever in the center position, and then tried to operate the dump bed, it was slower and jumpier while going up. It sounded like the pump was surging or something.

I repeated these two methods of operation a couple times to verify.

So I'm thinking that power beyond port's connection with the flow diverter box might be doing something weird and I should delete it.

What say you more experienced people?

Does this set up seem safe and functional?

Thanks!

 

[Hay Dude]

I just shut the pump lever off up at the engine driven pump.
Here was mine before I removed it.

 

[leadfarmer]

I'm not sure what you mean. I still need the hydraulic pump for the dump bed.

 

[rScotty]

I don't do well without a diagram, but it sounds like your question is about the Power Beyond Port on the first valve block.

A power beyond port is not just a port. It has one of two different sleeves added inside the control valve assembly depending if the PB port is used for flow or just capped off.

If the PB port is capped off, then you first slip in the sleeve that causes the PB flow to be added to the return line flow inside the control valve assembly.

If the PB port is to be used for pressure somewhere else, you have to use a different sleeve. That one is shaped so that it blocks the flow from joining the return flown inside the valve. Instead, it allows flow out the PB port.

If yours is plumbed the second way and you simply block off the PB port, you will certainly deadhead that PB flow and could damage the pump.

These internal sleeves are usually bronze and are often ordered with the valve because they are made for each specific model of valve. Sometimes if it is a popular valve, a place like surpluscenter.com will have one to fit...but unlikely. Otherwise, best to leave it as is, and take that PB flow somewhere to a another control valve that has a return but no PB port. Let that valve internal and it's passages do the work for you. Sounds like that may be what they've done on yours.

rScotty

 

[leadfarmer]

I don't do well without a diagram, but it sounds like your question is about the Power Beyond Port on the first valve block.

A power beyond port is not just a port. It has one of two different sleeves added inside the control valve assembly depending if the PB port is used for flow or just capped off.

If the PB port is capped off, then you first slip in the sleeve that causes the PB flow to be added to the return line flow inside the control valve assembly.

If the PB port is to be used for pressure somewhere else, you have to use a different sleeve. That one is shaped so that it blocks the flow from joining the return flown inside the valve. Instead, it allows flow out the PB port.

If yours is plumbed the second way and you simply block off the PB port, you will certainly deadhead that PB flow and could damage the pump.

These internal sleeves are usually bronze and are often ordered with the valve because they are made for each specific model of valve. Sometimes if it is a popular valve, a place like surpluscenter.com will have one to fit...but unlikely. Otherwise, best to leave it as is, and take that PB flow somewhere to a another control valve that has a return but no PB port. Let that valve internal and it's passages do the work for you. Sounds like that may be what they've done on yours.

rScotty

Thanks for looking at it. Here is a schematic that might help you help me. I think the flow divider box that still exists has some capability built in to shift flow where it is needed more. But I’m not sure. If it didn’t then it would just be a simple T connection. But i dont see how what i have now is different from what existed previously when the flow control box was turned off

 

[leadfarmer]

Here is a schematic of what it was before I made changes

 

[leadfarmer]

It sounds like I should connect the power beyond outlet to the tank. When the dump bed isn't being used and the pump is running the power beyond will dump all the fluid into the tank. When I use the dump bed valve the power beyond will be cut off and flow to the dump cylinder. Is that correct?

 

[rScotty]

It sounds like I should connect the power beyond outlet to the tank. When the dump bed isn't being used and the pump is running the power beyond will dump all the fluid into the tank. When I use the dump bed valve the power beyond will be cut off and flow to the dump cylinder. Is that correct?

First off, those are nice drawings - that makes it easy.

I think you can see the problem in the way it is now. The only way that works is if that diverter block has it's own (large) return line to the tank. You didn't show one, and so my bet is there is no place for that PB flow to go...

The PB flow out of the dump control valve is a flow with the potetial to build pressure. So it gets over to the diverter valve where it is going to somehow backpressure the innards of the diverter valve - all the time building enough pressure until some of that rogue PB flow can escape inside & join in the pressure line to your dump control.
I can imagine there is chaos inside that diverter valve. And while all of this is happening it is periodically building enough pressure to slow the main pump and probably dumping whatever it can via the relief valve - assuming that there even is a relief valve somewhere.

My bet is it oscillates, gets hot, and you should not do much of that.

When the auger and spreader were there, there was a use for that PB flow. Now it's problem and I don't know what to do with it using what you have there. You cannot just dump it into the sump, because there goes all your flow wasted and no power anywhere.

You could:
1. Switch to the right PB sleeve so you can plug that PB port. IF so, BE SURE to increase the diameter of the return line. And make sure the valve can handle that much return flow.
Best get the specs on that valve model before doing this.
2. Or you could get a diverter valve with a real return port and hook that up...which is not a bad idea anyway because a diverter should have a relief valve, and the fact that yours doesn't have a return line means it doesn't have relief.... and that would frankly scare me when being used on something with high dump truck flow & pressures.
3. Or you pitch the diverter AND the existing dump control in favor of a one lever control valve without PB but with a return port & relief valve. If you do that, you have to up the GPM of the control valve and probably all the pressure & return lines too. You may want to upsize the return lines anyway. I would.

My side worry is that I do not see a relief valve and line. Was it in the deleted parts?
rScotty

 

[leadfarmer]

The valve block return like is the same size as the line coming from the pump to the diverter box. Show left side, close, going down in the first photo. The second photo shows what I think is pressure relief valve by the valve block inlet. Im not seeing any identifying markings on the valve block.

 

[rScotty]

The valve block return like is the same size as the line coming from the pump to the diverter box. Show left side, close, going down in the first photo. The second photo shows what I think is pressure relief valve by the valve block inlet. Im not seeing any identifying markings on the valve block.

Typically the return line is at least twice the diameter of the pressure line, and even larger does't hurt. It needs to be able to return unused fluid to the sump without the fluid resistance of a small line that would put back pressure on the valve and cylinder.

Your original system had two return lines - one from the main valve body and another from the flow control for the auger and spreader.
So if now it just has the one return line from the main valve to handle the entire flow, that return line not only has to be much larger, but the main valve must be rated for enough GPM to be able to handle all the flow as well.

I'm not seeing a relief valve by the inlet in the second photo. Have you got a photo of the old flow control valve for the spreader and auger? Maybe one was there?

!!! One idea I just had is to put the auger & spreader control valve back into the circuit, but take off the handles and plug the cylinder ports so it cannot be actuated. Add a relief valve if it doesn't have one. Then you would have a place to put the PB line and also get back your original second return line. Also since the flow would be split, the original valves GPM rating is good. They can all handle their share of the flow.

The relief valve thing bothers me. Just lifting an empty bed doesn't build much pressure, but lifting a load will build real big pressure. And then drop it suddenly.
Plumbing in a relief right off of the main pump is easy and cheap. Look on surpluscenter.com
rScotty

 

[leadfarmer]

I attached a photo pointing to what someone told me was pressure relief on the valve body. The other pictures are the flow control valve that was removed.

How would I go about specifying the right pressure relief valve to add to the system

Many thanks!

 

[LouNY]

It sounds like I should connect the power beyond outlet to the tank. When the dump bed isn't being used and the pump is running the power beyond will dump all the fluid into the tank. When I use the dump bed valve the power beyond will be cut off and flow to the dump cylinder. Is that correct?

Correct, that is the way it will work well.
The original setup provided a set flow to the control valves with the rest of the flow going to the spreader. When a control valve was not being used that valve flow was looped back into the system for the spreader. When the plow was actuated the sander would have slowed slightly but still ran from the dividers flow and picked back up after the valve was returned to center.

 

[rScotty]

Is that the diverter? Whatever it is, I've added an arrow pointing at the relief valve.
Relief valves are adjustable. They can be opened up. Inside will be seals plus some sort of compression spring-loaded poppet or ball bearing that seals an orfice. Adjustment for pressure at which it opens is done by changing the preload on the spring. Some springs have a threaded adjuster, others use shims.
Either way changes the preload and thereforenthe psi at which it opens.

Most Ag machines run at 3000 psi max, but not all do. Don't screw around with psi; and only use rated hydraulic fittings. Plumbing fittings will often thread on, but please DON'T.

For finding a proper psi, look at the markings on your hoses and hose fittings. Then call the manufacturer and ask what working pressure that part number is designed for. Set relief at that pressure +- 10%. Be real suspicious if anyone tells you higher than 3000 psi for a working pressure.

On dumping the PB line straight to the tank like LouNY says is OK. It might work. It all depends on how much of the flow in your valve was designed to go to the PB. It might work if the PB flow is smaller than the main, but won't if the PB flow was designed to handle full pump output.
No way to know, different valves had different schemes. But I agree with Lou that it won't hurt to try. At worst you will just not get enough pressure to lift a load and we can work on one of the other ideas.

 

[leadfarmer]

That photo you added the arrow to is the flow control valve I removed.

The flow diverter is the square silver box still on the truck.

So it looks like the flow control valve I removed was acting as the relief for the the valve block and the flow control valve. Interesting. The return to tank hose on the flow control valve was a smaller size hose.

There are some "pipe" fittings still in the hydraulic connections. I removed more of them when removing stuff. And I'm guessing it was like that a long time. Not that it makes it ok, but it does seem that whatever pressure this system works at won't blow up those pieces immediately. But I understand shock loads and how things can happen to spike pressure.

 

[rScotty]

That photo you added the arrow to is the flow control valve I removed.

The flow diverter is the square silver box still on the truck.

So it looks like the flow control valve I removed was acting as the relief for the the valve block and the flow control valve. Interesting. The return to tank hose on the flow control valve was a smaller size hose.

There are some "pipe" fittings still in the hydraulic connections. I removed more of them when removing stuff. And I'm guessing it was like that a long time. Not that it makes it ok, but it does seem that whatever pressure this system works at won't blow up those pieces immediately. But I understand shock loads and how things can happen to spike pressure.

Yes, I'm sure the one I drew the arrow to is a relief valve. i didn't know which box it was on.

The one you are pointing to with your finger in the photo may be a relief valve. I've never seen one like that, but that means little. Kinda small, but It is on the main valve body and located where you would expect a relief valve to be on the valve body. Lets say it is a relief, and also there was a relief back on the flow control valve assembly. That makes the right number, and also puts them where they should be located in the circuit. Makes sense.

Are you going to try Lou's idea and just dump the PB to the sump? Whether that works or not .... and how well.... just depends on the geometry of the passages inside that particular main valve body. I don't see a down side other than the bed may have decent lift power for small loads but not much as the load increases. Reason for that is that flow tends to follow the easiest low resistance path - and that would be out the PB and to the sump. .
rScotty

 

[Hay Dude]

I'm not sure what you mean. I still need the hydraulic pump for the dump bed.

OK, I thought you were looking to remove it altogether. If you need pictures of my setup now that it’s done, I can send. I had a dump truck set up with hydraulic lines for bed auger, bed tilt & drop spinner

 

[leadfarmer]

I think the easiest solution is to put the flow control valve that I removed back where it was (but under the cab, not in it), and just have its return to tank connected. Block off the two lines it had feeding the auger and spreader. Then the system will effectively be back to how it was.

 

[rScotty]

I think the easiest solution is to put the flow control valve that I removed back where it was (but under the cab, not in it), and just have its return to tank connected. Block off the two lines it had feeding the auger and spreader. Then the system will effectively be back to how it was.

Yes, that would work. I wondered if we would come back to that.
In fact from message #10:

! One idea I just had is to put the auger & spreader control valve back into the circuit, but take off the handles and plug the cylinder ports so it cannot be actuated. Add a relief valve if it doesn't have one. (It does) Then you would have a place to put the PB line and also get back your original second return line. Also since the flow would be split, the original valves GPM rating is good. They can all handle their share of the flow.

rScotty